Method and apparatus for the production of inserts

ABSTRACT

A method for the production of inserts or the like is shown, with a patient or also a healthy person standing/walking/sitting/lying/biting in a defined position and/or movement with the body part to be fitted (foot, buttocks/back, teeth) on/over an electronic measuring arrangement for two- or three-dimensional measurement of the forces (pressures) acting on the measuring arrangement. The output signals of the measuring arrangement corresponding to the pressure-force distribution under the body part in the two- or three-dimensional pattern of the pressure-force distribution are relayed to a computer and compared with a stored set of desired values (wanted or ideal data). The differences between the distribution patterns are transformed into control signals for controlling an apparatus for the manufacture of the inserts or seating furniture surfaces, lounging furniture surfaces, dental prostheses, in such a way that upon addition of the (virtual) pressure force compensation distribution in accordance with the form (height) and/or rigidity of the inserts or the like to be manufactured to the actual pressure force distribution pattern, the desired pressure force distribution pattern essentially results.

BACKGROUND OF THE INVENTION

The invention relates to a method and apparatus for measuringparameters, and has particular applicability to the production of shoeinserts and the like.

The term "inserts" is to be understood here as a generic term fortechnical objects which are brought into force-locking and/orform-locking union with parts of the human body. A typical example areorthopedic inserts or insoles which are to be adapted to the foot of apatient, and also, of course, of healthy persons. Also involved isseating or lounging furniture which is to be adapted to the respectivebody parts of the user. Also it means prostheses or ortheses which areto he adapted to the stump of a limb. Further the invention alsoinvolves the adaptation of dental prostheses (full prostheses as well assingle teeth or crowns) which are to be adapted, especially taking intoconsideration the movement geometry of the chewing apparatus, to theopposite (natural or likewise artificial) teeth.

In making orthopedic inserts (and also e.g. prostheses or corsets)present practice is to perform a (three-dimensional) survey of the formsto be adapted or to be corrected. This survey can take place throughimpressions in thermosetting compounds or by direct (optical) surveying.In any case, therefore, one proceeds practically exclusively fromthree-dimensional contours, and moreover generally in the unstressedstate of the respective body part.

It has now been found that inserts, prostheses or also seating orlounging furniture made on the basis of these surveys are often felt bythe user to be unpleasant, annoying, etc. Moreover, the correctionresults are not optimal. Lastly, in particular in the case ofinserts/insoles, the problem exists that in many points the orthopedicshoemaker works "on intuition", so that the inserts made by him are notreadily to be manufactured on the basis of purely objective test data.When making dental prostheses the procedure is still more inaccurate,again simply a direct survey of the three-dimensional contours takingplace, namely by way of impressions in plastic compounds and subsequentgrinding down of "pressure spots" which appear on the dental prosthesiswhen biting on dyed paper.

OBJECTS AND SUMMARY OF THE INVENTION

Starting with the above stated prior art, it is an object of the presentinvention to develop a method and an apparatus of the initiallymentioned kind to the effect that at little cost improved results (withrespect to corrections, compatibility, etc.) can be obtained in asatisfactorily reproducible manner.

This problem is solved by the present invention. In particular that theforce distribution or respectively the two- or three-dimensional patternof the occurring forces is made use of to produce the inserts, seatingfurniture surfaces etc., and this in such a way that direct control ofthe machine manufacturing the parts becomes possible. By direct controlmust be understood here also the case as an inferior form of realizationwhere a conformable reproduction of the object to be manufactured isproduced by the computer and then (although somewhat laboriously) theobject is made according to this conformable reproduction. Comprisedhere also is the printout of corresponding sets of test data. In allcases, however, satisfactory factory reproducibility of the methodresults, whereby the quality of the resulting product is increased andat the same time the costs are reduced.

The manufacture of orthopedic inserts can here occur so that thecomputer-generated control data control a numerically controlled machinefor the manufacture of the insert itself. This can be done e.g. by millcutting, by appropriate hot or cold shaping with respect to thegeometric dimensions, an approximation to the "ideal" pressure patternbeing produced by the respective shaping, or excessive pressures atcertain points being absorbed or compensated (e.g. by depressions in theinsert). If the adaptation of prostheses is involved, it is possible bythe evaluation of the pressure pattern to achieve optimum adaptation ofthe denture or of the chewing surfaces to the movement geometry of thechewing apparatus, which at present is possible only by very complicatedthree-dimensional surveying. In particular there are taken intoconsideration in this case also three-dimensional test data, that is,shear forces acting at the chewing surfaces.

Another possibility within the invention is to determine, by numericalcontrol, only or additionally the hardness or rigidity of the materialof which the inserts or seating surfaces etc. are made. Site-dependentadjustment of e.g. the composition of a plastic of which the inserts (ormattress) are made or with which a chair blank is covered,site-dependent determination of the degree of foam expansion,site-dependent control of the setting of a hardenable plastic,site-dependent adjustment of the density of the material (e.g. bydrilling or pressing) etc. is then possible.

In a further, preferred embodiment of the invention, there is determinedin addition to the force distribution, at least in the regions in whichthe foot does not rest on the measuring platform under load, thedistance of the foot sole portions not in bearing contact from themeasuring platform, thus obtaining additional information for shapingthe insert in the sense of a compensation of "error forms" andtransmitting it to the insert-making machine.

If, instead of inserts, e.g. a chair or a motor vehicle seat is to beconstructed, one proceeds advantageously, not from a flat measuringplatform, but from a "standard chair" or blank, whose surfaces lyingopposite the body are equipped with respective force-measuring pickups(and preferably distance pickups in addition). When a patient sits onsuch a blank, there results in the measurement an "error pattern", onthe basis of which (taking into consideration the forms of the blank)the numerically controlled machine can then produce the seat cushionactually to be fitted to the subject. The same applies, of course, alsoto the fitting of prostheses. Here, too, therefore, what is involved isessentially the measurement of forces, their comparison with a set ofdesired values, and the automatic and hence exactly reproducibleproduction of seating furniture/prostheses/ortheses, after thecomputation of respective control signals, through numericallycontrolled machines.

The input of the control data into the machine for the production of theinserts, etc. need not occur on line; it may be carried out by hand, ashas been described at the beginning. So also it is possible inprinciple, instead of using numerically controlled machines, to makee.g. templates which serve for copying by hand. This inferior form ofrealization of the method is, of course, also comprised under theinventive idea.

BRIEF DESCRIPTION OF THE DRAWINGS

For better comprehension, preferred embodiments of the invention will beexplained more specifically below with reference to the illustrations.

FIG. 1 is a schematic layout of an apparatus for carrying out the methodaccording to the invention;

FIG. 2 is a side view of a measuring platform with a foot placed on:

FIG. 3 is a basic representation of the area labeled III in FIG. 2;

FIG. 4 is a further preferred form of realization of a distancemeasuring device; and

FIG. 5 is a detail of a single distance-measuring pickup from FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, a measuring platform 2 is connected to a computer 3,the output of which controls a numerically controlled milling cutter(drilling machine, etc.). This device for the production of the inserts(prostheses etc.) is provided with the reference number 4.

Preferably there are carried out not only purely static measurements,but the patient is made to run over the measuring platform 2 severaltimes, the resulting pressure distribution pattern being averaged. In sodoing, a correlation of the instantaneously measured "pressure pattern"with the previously measured pressure pattern is made with respect tothe position of the measurement plane. By this averaging a substantialimprovement of the insert fit is possible, as the actual pressurepattern is derivable not only with increased accuracy but also withexclusion of various falsifying influences (cramped body posture etc.).Furthermore a "dynamic" measurement is effected, which surprisinglygives much more information about the actual errors in the pressurepattern (as compared with a "normal" pressure pattern) than the purelystatic measurement. Many different platforms may be used, and amongothers, the system sold under the name of "EMED", reported e.g. in "Arztheute", page 3 (Oct. 16, 1985) can be used. Other types oflocus-resolving measuring platforms or measuring surfaces can be used aswell.

Instead of a rigid platform 2 there may be used (as also for theproduction of prostheses/corsets) a flexible measuring mat which (cutout in the form of an insert sole) can be placed in a shoe. The pressuredistribution pattern measurable while the subject walks (runs, stands)is then also influenced by the shoe itself, so that an additionaladaptation of an insert or insole to the shoe can also take place. Inparticular for the production of foot pads (for given shoes) this is ofadvantage. Further it is possible to provide additionally also a"standard insert" between shoe and measurement insert, which is thencorrectable with reference to the measurement data obtained and is thusadaptable to the foot and shoe simultaneously.

FIG. 2 illustrates a foot 1 placed on a measuring platform 2, in sideview. On the measuring platform 2 are shown schematically further thedata pickups, e.g. capacitive pickups. It is evident from thisillustration that in the region between heel and forefoot a region 5exists in which the foot (except for an extreme flat foot) rests on themeasuring platform 2 or respectively on the surface thereof. This regionIII is now measured ("metered") preferably with respect to its geometricdimensions in addition to the pressure distribution measurement, to beable to manufacture the insert (prosthesis, corset) accordingly. Apreferred form of realization of an arrangement for the measuring ofsuch spaces is shown in FIG. 3.

Here, close to the surface of the measuring platform 2, a foil (film) 10is applied which with the surface of the measuring platform 2 can form acavity which through a conduit 15 can be filled with a liquid 9. To thisend the conduit 15 communicates with a pressure-generating unit 11 whichin the example shown in FIG. 3 comprises a space 13 filled withcompressed gas, which space is separated by a diaphragm 12 from areservoir 14 for liquid 9. If the volume is made large enough, thisarrangement acts so that a pressure largely independent of the geometricdimensions prevails in the liquid 9, so that the foil 10 presses ontothe foot sole with constant force.

On the surface of the measuring platform 2 or respectively substantiallydirectly on the sensors 7, piezoelectric transducers 6 are arranged,which are connected to the computer 3 via an actuating and evaluatingcircuit 17. The piezoelectric transducers 6 transmit (pulsed) ultrasonicsignals (arrows in FIG. 3), which are reflected by the foil surface 10and received by the same (possibly by additional) piezoelectrictransducers and relayed to the evaluating circuit 17. From the transittime differences the distance of foil 10 and hence of the foot sole inthe region not making contact is measurable. Preferably the transducers6 are designed as piezoelectric foil which are contacted on both sidesthrough conductor runs arranged in matrix form. Thereby a separateactivating and/or polling of the transducers is possible to obtain athree-dimensional pattern. Further it is of advantage if severalpiezoelectric transducers 6 are combined to obtain a directionalcharacteristic, thereby further improving the locus resolution of thismeasurement arrangement. By the liquid filling very high frequencies, avery high resolution is possible; and the sensitivity of the systemincreases due to the low attenuation in the liquid.

In another preferred embodiment of the invention not shown here,inductive or capacitive pickups are provided instead of piezoelectrictransducers 6, in which case the foil 10 is then preferably metallized.

In the form of realization shown in FIG. 4, the distance between themeasuring platform 2 and foot 1 is measured through a spring-ramarrangement, which are applied standing side by side on a rigid platform2 and uniformly covering the measurement surface thereof. Each springram 16 (also shown diagrammatically in FIG. 3) comprises a housing 117,in which a ram 18 telescopes. Each ram 18 is pushed away from theplatform 2 by a spring 19, its seating being formed by a cover 20 in thehousing 117. The strength of the springs 19 is made so low that wherethe foot, when standing, rests on a flat, hard support, the springs 19are completely compressed. Only in the regions in which, due to itsform, the foot is spaced from a flat, hard platform, the rams 18 areextended. Each ram 18 then exerts through the spring 19 and the bottom20 a force on the measuring platform 2, the amplitude of which isinversely proportional to the length of the spring 19 and henceproportional to the distance of the respective foot section from thearea defined by the completely pressed-in rams. By measuring theseforces, therefore, the distances can be determined at the same time.

The arrangements shown in FIG. 2 to 5 can serve also for optimum designof lounging furniture. In a preferred embodiment of the invention, notshown in the illustrations, one proceeds however, for the production oflounging or seating furniture, from a blank, the form of which isadapted to average values. Such blanks are then provided with anarrangement of pressure force pickups 7. For the production ofprostheses the equivalent applies.

For the production of dental prostheses is suitable in particular aflexible measuring arrangement (as can be used e.g. also as insert soleas described above) the small thickness being of importance here toavoid impermissible falsification of the movement geometry of thechewing apparatus by the measuring arrangement.

I claim:
 1. A method for the production of inserts and the like for aperson, comprising the steps of:electronically measuring a spatialpattern of forces applied by the person to a measuring arrangement;producing output signals in correspondence with said measured forces;supplying said output signals to a computer; comparing said suppliedoutput signals in the computer with stored signals corresponding to astored set of desired values of a force distribution pattern; producingcontrol signals in response to differences between said output signalsand said stored signals; controlling apparatus for making the insertsand the like in response to said control signals such that a desiredforce distribution pattern results.
 2. A method according to claim 1;further including the step of applying said forces to a portion of saidmeasuring arrangement by contact of the person with a surface of themeasuring arrangement in which a portion of said surface is notcontacted by the person; and said step of electronically measuringincludes the step of 3-dimensionally scanning distances between saidperson and portions of said surface of the measuring arrangement thatare not contacted by the person by means of distance sensors; saidstepof producing output signals includes the step of producing outputsignals by said sensors such that the output signals correspond to adistance pattern between the person and the measuring arrangement andsaid stored set of desired values correspond to a desired distancepattern.
 3. A method according to claim 1; wherein said output signalsare averaged over a plurality of measurements as varying forces areapplied by the person to the measuring arrangement.
 4. A methodaccording to claim 1; wherein said step of controlling includes a stepof controlling the apparatus so as to control the height and/or rigidityof the inserts and the like in accordance with a conformablereproduction of the stored set of desired values.
 5. Apparatus formaking inserts and the like for a person, said apparatuscomprising:electronic measuring a spatial pattern of means for measuringforces thereon; and for producing output signals in correspondence withsaid measured forces; computer means including storage means for storingstored signals corresponding to a stored set of desired values of aforce distribution pattern and comparison means for producing controlsignals in response to differences between said output signals and saidstored signals and for controlling apparatus for making the inserts andthe like in response to said control signals such that a desired forcedistribution pattern results.
 6. Apparatus according to claim 5; whereinsaid electronic measuring means includes a surface on which forces areapplied by a person and a plurality of distance sensor means for3-dimensionally scanning distances between a body part of the person andthe surface of the measuring means to produce said output signals, saidplurality of distance sensor means being connected to the computermeans.
 7. Apparatus according to claim 6; wherein said distance sensormeans are effectively provided directly on the surface of the measuringmeans.
 8. Apparatus according to claim 6; wherein said distance sensormeans include contactless measuring sensors.
 9. Apparatus according toclaim 8; wherein said distance sensor means are one of capacitance andinductance sensors which measure the transit time of one of reflectivelight and ultrasonic waves.
 10. Apparatus according to claim 5; whereinsaid measuring means include a matrix arrangement of force pickup meansfor measuring said forces.
 11. Apparatus according to claim 5; whereinan arrangement for application of defined forces to body part regions ofthe person is provided between the measuring means and the sole of afoot of the person not in contact with the surface of the measuringmeans.
 12. Apparatus according to claim 11; wherein said arrangement forapplication of defined forces includes a foil applied tightly on thesurface of the measuring means; at least one conduit means for supplyingfluid to a space between said foil and said surface of the measuringmeans and pressure generating means for supplying fluid under pressurethrough said at least one conduit means to said space such that the foilapplies a force essentially completely on a body part to be measured;and wherein said distance sensor means include ultrasonic sensors forradiating ultrasonic waves directly into the fluid-filled space betweenthe foil and the surface of the measuring means.
 13. Apparatus accordingto claim 12; wherein said ultrasonic distance sensors include a matrixarray of piezoelectric foil having surfaces which are contacted viacrossing conductor runs and are excited and/or polled via a multiplexerarrangement.
 14. Apparatus according to claim 5; wherein said apparatusfor making inserts and the like includes a CNC milling cutter for theproduction of pourable molds and/or deep drawing molds.
 15. Apparatusaccording to claim 5; wherein said apparatus for making inserts and thelike includes a plastic molding machine to which control signals forsight-dependent adjustment of material rigidity are suppliable.